The invention relates to a handlebar for vehicles, in particular, for motorcycles and bicycles, comprising a tubular, straight center section, preferably of round cross section, two tubular, straight outer sections, preferably of round cross section, the center axes of the two outer sections not coinciding with a center axis of the center section and the outer diameter of the two outer sections being smaller than that of the center section, and two hollow, bent sections joining the center section and the two outer sections, the outer diameter of the two hollow, bent sections tapering from the center section to the outer sections.
Such handlebars are known, for example, from U.S. Pat. No. 5,117,708. These handlebars are of tubular design, and the cross-sectional area of the tubes is the same size at every point so that the wall thickness is smallest in the center section and largest in the outer sections.
This wall thickness configuration involves a waste of material and an unnecessary increase in the weight of the handlebar, for the bending moment is smallest at the outer sections. Furthermore, the increasing of the wall thickness as compared with the highly stressed center section does not conform with the theoretical requirements, even if the outer diameter is reduced, as the dimensioning of the wall thickness has to be adapted to the requirements of the center section.
A further handlebar is known from U.S. Pat. No. 5,257,552. Herein the stress-related requirements are met insofar as the wall thickness is largest in the center section and smallest in the outer sections. However, the fact that the handlebar is not only stressed by the bending moments during the steering but also undergoes further stress by being clamped at the center section thereof to the vehicle and by the fittings, for example, brake lever, throttle lever, being clamped to the outer sections thereof is not taken into account.
Therefore, if the center section is dimensioned in a material-saving way such that the bending moment and the clamping force can be absorbed, and, if the wall thickness is smaller at the outer sections, this will then be adequately dimensioned for the bending moments which occur, but not for the clamping.
There is thus the danger that the tube will undergo deformation in the region of the outer sections and the fittings will, consequently, become detached.
This danger is further heightened by the fact that such handlebars are generally made of aluminum, the modulus of elasticity of which is only about a third of that of steel.